Unloading means for air-compressors.



No. 730,121. 7 PATENTED JUNE 2, 1903. E. HILL. x UNLOADING MEANS FOR AIRCOMPRESSORS.

APPLICATION FILED NOV. 12, 1902.

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No. 730,121; PATENTED JUNE 2, 190a. E. HILL.

. UNLOADING MEANS FOR AIR GOMPRESSORS.

APPLIOATION FILED NOV; 12, 1902.

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'necting the escape-valve UNITED STATES Patented Tune 2,1903.

PATENT OFFICE.

EBENEZER HILL, OF NORWA'LK, CONNECTICUT.

UNLOADING MEANS FOR AIR-COMP RESSORS.

SPECIFICATION forming part of Letters Patent 1\To. 730,121, dated June2, 1903.

Application filed November 12,1902. Serial No. 130,956.

(No model.)

T0 61/ whom it may concern.-

Be it known that I, EBENEZER zen of the United States, residing atNorwalk, in the county of Fairfield and State of Con necticut, haveinvented certain new and useful Improvements in Unloading Means forAir-Compressors, of which the following is a specification.

This invention relates to a means for auto matically stoppingcompression and relieving the pumping-pistons of a multiple-stagecompressor from load when the pressure in the system exceeds the desiredamount and continuing compression when the pressure in the system dropsto normal.

The object is to provideavery simple,cheap, and quick-acting means forrelieving all of the pumping-pistons of the compressor from work whenthe pressure in the system rises above the predetermined maximum. Thisobject is accomplished by connecting an escape-valve with the ductbetween cylinders which operate at difierent pressures and conwith thesystem in such manner that the escape-valve will be opened'when thepressure in the system rises above normal and allow air to escape fromthe interduct and relieve the low-pressure piston of load. Thesuction-valves of the high-pressure cylinder are held open when thepressure in the interduct drops, so that the high-pressure piston willnot force air forward to the receiver when the escape-valve is open andthe low-pressure piston is relieved from work.

Figure 1 of the accompanying drawings is a side elevation with partsbroken away of connected high-pressure and low-pressure cylinders of acompound air-compressor em bodying the invention. Fig. 2 is a centralvertical section, on larger scale, of the escapevalve that is connectedwith the interduct of this compressor. Fig. 3 is a longitudinal section,on large scale, of a suction-valve of the high-pressure cylinder that isheld open when the pressure in the interduct drops below normal.

The first or low-pressure cylinder 1 has ordinary suction-valves 2,discharge-valves 3, and piston 4. The second or high-pressure cylinder 5has special suction-valves 6, ordinary discharge-valves HILL, a citidiskis guided in its 7, and piston 8. The two cylinders are joined in theusual manner and are connected by an intercooler 9, and the two pistonsare connected by a rod 10 and are adapted to be connected with asteampiston. The discharge from the high-pressure cylinder is connectedwith the receiver 11, from which the air is supplied to the system atthe desired pressure. Connected with the interductthat is, theductthrough the intercooler from the loW to the high pressurecylinders-is an escape-valve 12. The upper end of the escape-valvecasing is open to the atmosphere, and in the upper part of the casingand adapted to close the escape-port is a valve-disk 13. This valve-diskis connected by a rod 14 with a plunger 15. The valvemovement toward andfrom the seat around the port by a disk 16, that is attached to a post17, fastened to a bar 18, that is secured across the opening at the topof the casing. The disk 16 fits loosely and lies in a chamber 19 in thevalve-disk, the upper and lower ends of which chamber are connected by apassage 20., A ball 21 controls the opening from the lower part of thechamher to this passage. When the valve-disk moves away from its seat,the air in the lower part of the chamber beneath the disk escapes slowlypast the edges of the disk and acts as a cushion and requires thevalve-disk to open gently. When the valve-disk closes, the air travelsfreely from the upper to the lower portion of the chamber through thepassage 20, so that the closing will be quick.

The plunger is connected by a rod 22 with a weight 23 outside of thecasing. The weight normally holds the valve closed. On the weight-rod,which fits loosely in the opening through the lower end ofthevalve-cylinder, is a hand-nut 24, which may be turned on the threads cuton. the rod, so that by engagement with the bottom end of the casing itwill limit the upward movement of the valvedisk or look it againstmovement.

Thereceiver is connected with the escape valve casing below the plungerby a pipe 25. In this pipe is an automatic pressure-valve 26 of ordinaryconstruction. When the pressure in the receiver rises sired degree, thepressure-valve is opened higher than the deagainst its spring, so thatthe pressure in the receiver will be exerted on the plunger and cause itto lift and open the valve, so that air will discharge from theinterduct to the atmosphere. This renders the first or low-pressurecylinder-ineffective without stopping the engine or the movements of thepistons. When the pressure in the system is reduced to normal, thepressure-valve is closed, and the piston, relieved from thesystem-pressure, is drawn down by the Weight as the air below it escapesthrough the opening about the rod 22 and the escape-valve is closed.

The suction-valve 27is fastened to a spindle 28, that is supported by ahub 29, held in the cylinder-head 30. A spring 31, thrusting between theflange 32 of the hub and the head 33 of the spindle, tends to keep thesuctionvalve closed in the usual manner.

In the plug 34, that is'screwed into the cylinder-head, is a plunger 35,that closely fits the bore of the plug. The plunger is connected with arod 36, that has a collar 37 movable in an opening in the end of theplug. A spring 38, thrusting between the end of the plug and theplunger, tends to force the plunger toward the head of the spindle. Anopening 39 through the flange of the spindlehub allows the air-pressurein the inlet-port 40 in the cylinder-head to be exerted outwardlyagainst the plunger. This pressure, when normal,overcomestheforceofthespring back of the plunger and holds the plunger away fromthe head of the spindle, allowing the suction-valve to operate freely inthe usual manner. When the pressure in the inlet-port is reduced belownormal, as when the iuterduct is relieved of pressure by the opening ofthe escape-valve and the lowpressure piston is put out of commission,the spring thrusts the plunger against the head of the spindle and holdsthe suction-valve open. With the suction-valve open the highpressurepiston is put out of commission, for it merely draws air in and pushesair out through the open inlet-ports.

When the pressure of the airin the receiver exceeds the desired maximum,the pressurevalve in the connection between the receiver and theescape-valve is opened and the system-pressure is exerted on the underside of the plunger, so as to lift it and open the escape-valve andallow the air which has been pumped into the inter-duct by thelow-pressure piston to escape to the atmosphere. This renders the 10w-pressure piston inelfecti've and causes a drop of pressure in theinterduct. This drop of pressure in the interduct relieves the pressureon the plunger back of the suction-valve, so that the spring will causethe plunger to hold the suction-Valve open and put the high-pressurepiston out of commission. The parts remain in this relation until thepressure in the system falls to normal. Then the pressure-valve in theconnection between the receiver and escape-valve closes and allows theweight to close the es- When the escape-valve is closed, the pressure inthe interduct immediately rises, and as the pressure in the interductreaches normal the suction-valve is freed, so that it can resume itsnatural function. By reason of this simple construction the high and lowpressure pistons are rendered ineffective and the engine quicklyrelieved of load without being shutdown when the pressure is greaterthan desired and without waste of energy.

The invention has been illustrated and described as applied to acompound compressor; but it is equally applicable for compressors havingmore than two stages of compression, and while the term air-compressorhas been used throughout the specification it is to be understood thatthe term air is intended to apply to any gas. The specification hasdescribed but one suction-valve. The high-pressure cylinder ofcompressors of this class is provided with more than one suction-valve,and any number of these suction-valves may be provided with the meansfor holding them open when the pressure in the interduct drops.

I claim as my invention- 1. In a multiple-stage compressor, thecombination with cylinders operating at different pressures, of anescape-valve controlling an outlet from the duct between the cylinders,a communication between the system beyond the high-pressure cylinder andsaid escapevalve, whereby-the escape-valve is moved to open the outletfrom the interduct when the pressure in the system beyond thehighpressure cylinder exceeds the predetermined maximum, and a valvecontrolling an opening into the high-pressure cylinder and adapted to berendered inoperative by the drop of pressure resulting from the openingof the escape-valve, substantially as specified.

2. In a multiple-stage compressor, the combination with cylindersoperating at difierent pressures, of an escape-valve controlling anoutlet from theduct between the cylinders, a communication between thesystem beyond the high-pressure cylinder and said escapevalve,Wherebythe escape-valve is moved to open the outlet from the interductwhen the pressure in the system beyond the high-pres sure cylinderexceeds the predetermined maximum, a pressure-valve controlling thecommunication between the system beyond the high-pressure cylinder andthe escapevalve, and a valve controlling an openinginto thehigh-pressure cylinder and adapted to be rendered inoperative by areduction of the pressure between the cylinders, substantially asspecified.

3. In a multiple-stage compressor, the combination with cylindersoperating at different pressures, of an escape-valve controlling anoutlet from the duct between the cylinders, means for keeping theescape-valve closed, a communication between the system beyond thehigh-pressure cylinder and said escapecape valve.

valve, a pressure-valve controlling the communication between the systembeyond the high-pressure system and the escape-valve, and asuction-valve of the high-pressure cylinder adapted to be held openwhenever the pressure is reduced in the duct between the cylinders,substantially as specified.

4:. In a multiple-stage compressor, the combination with cylindersoperating at different pressures, of an escape-valve connected with theduct between the cylinders, means for keeping the escape-valve closed, aplunger connected with the escape-valve, and a communication between thesystem beyond the high-pressure cylinder and the escape-valve casingbelow the plunger whereby, when the pressure in the system exceeds thepredetermined maximum, it will actuate the plunger sure drops belownormal, substantially as 30 speci fied.

EBENEZER HILL.

Witnesses:

E. HILL, Jr., 1-1. H. MOSSMAN.

